This invention relates to devices and methods for applying thermal therapy to living tissue.
Thermal therapy involves the application of heat or cold to tissue to heal and rehabilitate injuries, such as, bruises, sprains, or other trauma to bone, muscle, ligaments, tendons, and skin. Cold therapy can be used to reduce swelling, reduce pain and promote healing of injured tissue. Heat therapy can be used to loosen joint tissue, such as, ligaments and tendons, to increase range of motion, e.g., before strenuous activity. Thermal therapy can be used after surgery to reduce pain and swelling and promote healing. Thermal therapy can also be used as part of an orthopedic therapy program, a sports medicine program, and to heal and rehabilitate animals, such as, thoroughbred race horses.
Common thermal therapy methods, e.g., application of an ice bag or a hot water bottle, are difficult to hold in place, are statically applied, cause uneven cooling or heating across the treatment site, and do not allow the cooling or heating temperature to be readily controlled.
A number of devices have been proposed for applying cold therapy to living tissue, with or without pressure. One device that has been developed for cooling a human knee includes a large cooler that contains chilled water which is circulated through a tube and into a cooling pad. The cooling pad is applied to a desired therapy site and held in place by a strap. The cooling rate is adjusted by increasing or decreasing the flow resistance through the tube leading to the cooling pad. Miller U.S. Pat. No. 2,531,074 describes a device which includes a flexible, multi-chamber thermal pad into which heated or cooled water is alternately injected at high and low pressures to provide temperature-controlled message therapy. Chessey U.S. Pat. No. 2,726,658 describes a system in which a coolant is pumped directly from a thermostatically-controlled refrigeration system into a cooling pad. Grossan U.S. Pat. No. 3,993,053 describes a massaging pad that includes a set of elastic tubing coils through which temperature controlled fluid is pulsed at high and low pressures to achieve a massaging effect. Copeland U.S. Pat. No. 4,149,529 describes a system that delivers heated or cooled liquid into a dry appliance for performing temperature and intermittent compression treatment; the system also provides a thermal therapy bath treatment.